1. Field of the Invention
The present invention relates to an electrical drive, hereinafter designated as a rotary actuator and in particular, a rotary actuator that can easily be controlled and regulated, which is distinguished by high accuracy, a high dynamic response and a compact build.
2. Description of the Prior Art
In many technical sectors the necessity exists for control of the movement or manipulation of objects by electrical control. Here the required movement of the objects can be a linear movement, a rotational movement, or a movement ensuing from the superposition of linear and rotational movements, in particular a movement along any trajectory. In many cases the requirement exists for the execution of rotational movements, or pivotal movements of a rotational nature, of objects, wherein the rotational movement in many cases is limited to a range of angles, but is to take place in as dynamic and accurate a manner as possible. Examples of applications of such requirements are found in the sectors of optics, mechanics, hydraulics, pneumatics and electrically powered devices. Optical deflection units are widely used; in these an optical element, for example a mirror, a lens, or an aperture, is pivoted into the optical path, or rotated in the optical path. Such deflection systems or deflection units find technical application in, inter alia, laser beam cutting processes, in laser printers as scanning mirrors, or in optical projection systems, such as head-up displays (HUD) for purposes of adjustment of the projection mirror and lenses. Tracking systems are a further field of application.
Also in the hydraulics and pneumatics sectors rotationally moved valve elements are often introduced alongside linearly moved valve elements, in order, for example, to be able to open and close an electrically controlled inlet or outlet. For purposes of proportional control of a volumetric fluid flow the valve elements must not only be able to open and close the fluid opening completely, but must be able to assume any intermediate position.
Pivotal and rotational devices are also widely used in the sectors of automation technology, production technology and medical technology, where they serve to manipulate and/or transfer objects, such as in automatic placement machines, or serve as switches that can be electrically actuated. In the four- and two-wheeled motor vehicle sectors, actuators of this type can be introduced into gearbox transmissions, or in the case of bicycles and/or electrical bicycles can be introduced for the electrical actuation of the derailleur gear for a chain transmission.
The technical problem and challenge for such electrical rotary actuators is in the adjustment of objects that are subject to inertia and mass with a high dynamic response, but also with accuracy.
Today galvanometers or galvanometer scanners are mainly deployed for purposes of optical beam deflection; these have a low mass mirror and an electrical deflection unit, usually electromagnetic or electrostatic in nature, for the mirror. With low inertia mirrors a high dynamic response and high accuracy can be achieved. A high dynamic response and accurate movement of objects of greater mass are not possible with such systems. Thus the field of deployment of galvanometer deflection systems is severely limited.
For the rotational activation of objects of greater mass electromagnets or electric motors are used in accordance with prior art. Here, however, a conflict of objectives exists between highest possible dynamic response and highest possible accuracy, in that only one of the objectives can be optimized at a time to the detriment of the other. The electrical rotational and pivotal drives that can be found commercially represent in this regard a compromise between the accuracy required and the dynamic response that can be achieved.